^OCTOBEB 4, 1912] 



SCIENCE 



445 



Only two successful matings of blond 

 hybrid Fj ring-doves inter se were made, as 

 blond hybrid females were seldom obtained. 

 The expectation for such a cross is given in 

 the following formula. Males and females of 

 both colors were obtained, but their composi- 

 tion was not tested. 



.5. Blond Fi hybrid 



Blond Fi hybrid 

 ^ females. 



Bd' (W?) B? (W^) 

 fBd- 



producing j Bc^J BJ 



gametes ] W(? WJ 



result: Blond males Blond females 

 Bd-BCS) B?B(c?) 



and also and also 



B<? (W5) B5 (W^) 



White males White females 



W<?W(?) WSW(<:?) and also 



B9W„(c?) or 



WJWCc?) 



A more detailed description of the results 

 "which were obtained by the writer in crossing 

 xing-doves has been prepared for publication, 

 .and a preliminary statement" has appeared in 

 this journal. 



The interesting results, recently described 

 "by Cole,' are easily explained by this scheme 

 Tvhen we recognize that yellow, dun, red, etc., 

 in pigeons are due essentially to less intense 

 melanin pigmentations than that which is 

 represented in black. The dun females in 

 Ijoth of Cole's " Cases I. and II.," would then 

 be due to conditions in the female-determining 

 sperms of the recessive male (designated by 

 subscript j^ in the formula used in this art- 

 icle). The occurrence of red, yellow and dun 

 in the offspring from the reciprocal cross is 

 not surprising when the uncertain purity of 

 domestic-pigeon stock is considered. Durham 

 and Marryat compared their canaries on the 

 hasis of eye-color, as the numerous color 

 variations of the plumage were less satisfac- 

 tory characters. 



E. M. Strong 



' Science, N. S., Vol. 33, p. 266, 1911. 

 ' Science, N. S., Vol. 37, pp. 190-192. 



FURTHER NOTE ON THE RESULTS OP OVARIOTOMT 

 ON DUCKS 



On July 26 of the present year, one of the 

 ducks (No. 24, now three years old) on which 

 ovariotomy had been performed as recounted 

 in the Biological Bulletin, Vol. XX., No. 1, 

 1910, was killed and dissected. In my orig- 

 inal report I stated simply that the bird was 

 castrated, but made no statement concerning 

 the completeness of the ovaries' removal. It 

 is the purpose of this note to supply this lack. 

 But before proceeding to describe the results 

 of the autopsy, certain points should be 

 briefly reviewed. 



August 13, 1909, the left ovary was re- 

 moved, no attempt being made to remove the 

 right gonad, which it was assumed had com- 

 pletely degenerated. The duck was then 12 

 weeks old and already had the secondary sex- 

 ual characters of the female which are dis- 

 tinct from those of the young male. For 

 nearly a year afterwards this bird passed as 

 an ordinary female. Then it was observed 

 that a part of her feathers were like those of 

 a male. At a moult soon after, she assumed 

 still more of the male's characters, being in the 

 condition shown in Fig. 11 of my earlier re- 

 port. Subsequently, still more of the male's 

 characters were acquired until her plumage 

 was predominately, yet incompletely, male. 

 For the last 18 months or so the plumage has 

 remained in this intermediate condition, 

 though several moults have occurred in the 

 meantime. 



At the autopsy no trace of an ovary on 

 either side could be found. The only duct 

 present was a well-developed but juvenile ovi- 

 duct on the left side. 



The other duck (No. 4), described in the 

 paper referred to above, was examined through 

 an opening in the left side on August 22. The 

 site of the ovary was empty except for a thin 

 strand of connective tissue. As far as could 

 be seen from the left, the right side also was 

 completely empty. This duck, operated on 

 when nearly a year old, had laid several eggs 

 in the period immediately preceding the 

 operation. One was removed from the ovi- 

 duct at the operation. She has developed only 



